1. Field
The present disclosure relates generally to communication systems, and more particularly, to extending a length of a cyclic prefix used for transmitting signals in a wireless communication system implementing a mixed carrier design.
2. Background
Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasts. Typical wireless communication systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power). Examples of such multiple-access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single-carrier frequency divisional multiple access (SC-FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems.
These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate on a municipal, national, regional, and even global level. An example of an emerging telecommunication standard is Long Term Evolution (LTE). LTE is a set of enhancements to the Universal Mobile Telecommunications System (UMTS) mobile standard promulgated by Third Generation Partnership Project (3GPP). It is designed to better support mobile broadband Internet access by improving spectral efficiency, lowering costs, improving services, making use of new spectrum, and providing better integration with other open standards using OFDMA on the downlink (DL), SC-FDMA on the uplink (UL), and multiple-input multiple-output (MIMO) antenna technology. However, as the demand for mobile broadband access continues to increase, there exists a need for further improvements in LTE technology. Preferably, these improvements should be applicable to other multi-access technologies and the telecommunication standards that employ these technologies.
In an MBSFN transmission structure implementing a MBSFN-dedicated carrier design, an entire carrier may be used for MBSFN traffic. However, no unicast traffic is carried or transmitted using such structure. Therefore, the MBSFN-dedicated carrier inefficiently utilizes system resources because of its inability to transmit/receive unicast services. Moreover, in some deployment scenarios, usable signal energies may arrive later at a receiver because of greater propagation delay due to a larger cell size. In such scenarios, a currently used cyclic prefix (CP) length may not be sufficient to capture all usable MBSFN signals, resulting in lower MBSFN gain, because usable signals having longer propagation delay may appear as noise. Accordingly, the disclosure solves the previous problems by providing an MBSFN transmission structure implementing a mixed carrier design, wherein unicast and MBSFN signaling is performed, and an extended MBMS CP length is used to allow MBSFN signals with longer propagation delays to be combined at the receiver.